Code communication system



May 8, 1962 F. w. BRIXNER com: COMMUNICATION SYSTEM 3 Sheets-Sheet 1 Filed Deo. l5, 1958 HIS AGENT May 8, 1962 F. w. BRIXNER CODE COMMUNICATION SYSTEM 3 Sheets-Sheet 2 Filed Dec. l5, 1958 INVENTOR F. W. BRIXNER m L gwoomwmm ov zoc HIS AGENT May 8, 1962 F. W. BRIXNER CODE COMMUNICATION SYSTEM 5 Sheets-Sheet 5 Filed Deo. l5, 1958 INVENTOR F.W BRI X NER @55mm OZEZDOU MM/agm HIS AGENT tates This invention relates to communication systems, and it more particularly pertains to the communication part of a centralized trafic control system for railroads.

In a centralized traiiic' control system for railroads, railway tratiic over an extensive stretch of trackway is controlled from a centralv control oftice, there being several remotely spaced field stations along the trackway at which switch and signal devices 'are located, and other signaling equipment, for governing railway traffic. The intelligent designation by an operator at a control oilice of controls for the different devices is dependent upon the operator being informed by indications registered on a control panel as to the conditions of the devices at the several field stations.

According to the present invention, a shunt type line circuit is provided connecting the control oice with the several field stations. Control codes are transmitted from the control oce for governing the devices at the eld stations as direct current code pulses duringv control cycles of operation. Step timing oscillators are used at the control oice and at all of lthe ield stations in conjunction with counting relays for determining the duration of the code elements andthe number of steps constituting each cycle of operation.

When a device is operated at a field station in accordance with a control codetransmitted from the control oiiice, the change in its condition initiates the transmission immediately of an indication cycle from that held station to register the new condition of the device at the control office. This is possible, irrespective of the number of eld stations, Without interfering with the transmission of indications from other eld stations, because of communication being maintainedwith each field station on a distinctive carrier frequency. Upon initiation of an indication cycle at any tleld station, an associated step timing oscillator and counting relays are initiated, and at the same time, an indication stepper at the control office provided for the particular field station transmitting is also initiated. By this organization, the control otlice can receive from several field stations at the same time, without the communication from one eld station interfering with another, and also at the same time, the control ofiice can transmit designated controls for any one of the eld stations.

An object of the present invention is to provide for the communication of switch and signal controls and indications in a centralized traiiic control system in such a mauner as to permit controls and indications to be transmitted at the same time and as to permit several field stations to transmit their indications at the same time.

Another object of the present invention is to permit immediate indication of the devices at the control ofi-ice from the several iield stations without interfering with the transmission of designated controls for the several field stations. f

Other objects, purposes and characteristic features of the present invention will be inpart obvious from the accompanying drawings and in part pointed out as the description of the invention progresses.

ln describing the invention in detail, reference is made to the accompanying drawings in which similar letter reference characters have been used to designate parts having similar features or functions and in which:

FlG-S. 1A, 1B and 1C when placed end to end respectively illustrate a centralized traic control system em- EC@ Y.

ploying one embodiment of the code communication apparatus according to the-'present invention.

The illustrations employed have been arranged to facilitate' the disclosure .ofi'the invention as to its mode of Thus certain components of the apparatus are illustrated in block form, and relays `and their' contacts are shown in a conventional manner, and the symbols (-l-) and` have been used to identify respective positive and negativek terminal ofV suitable batteries or other sources of direct current and the symbol (CN) has been usedkto indicate connection to the center tap of a suitable battery or other source of direct current. s

For the purpose of simplifyingv this disclosure of the present invention, the present invention is shown as being applied to a relatively simple track layout that may be considered as being a typical part of an extensive track layout, orV that may be consideredl as just illustrating typical organizations that may be applied by a person skilled in the art to the control of track switches and signals in diiferent and more complex arrangements Vof track switches and signals in more extensive track layouts.

The track layout for one embodimentf'of the present invention is illustrated in FIGS. 1B andl 1C as comprising a stretch of single track 10 havingassociated therewith passing siding 11 connected to track 10 by track switches 1W and '2W at the respective left-hand and righthand ends thereof; Eastbound signals IRA and IRB areV provided for governing eastbound traiic through `the track switch 1W, and the signals yILA and lLB are provided for governing westbound traiic through this'track switch.

lSimilarly, the signals ZRA and ZRB are 'provided for governing eastbound traic through the track switch 2W, and the signals ZLA and ZLB are .provided for governing Y westbound traffic Athrough this track switch. The signals at the left-hand end of the passing siding 11 are at eld station No. 1, and the signals at the Vrightehand end of passing siding 11 are at field station No. 2.

A pair of line wires 12 connect the control oice with the ield stations in a manner to maintain `a continuous connection whereby the wires may also be used for telephone communication lor for other purposes in accordance with the requirements of practice.

Control transmitting apparatus is provided at the control oice `as is illustrated in FIG. 1A including positive and negative code transmitting relays PC and NC respectively, a line battery LB, a Step Timing Oscillator 13,

lCounting Relays 14'and Station and Switch and Signal Control Code Selecting 'Apparatus 15. A suitable Low Pass Filter 16 is employed to connect the direct current code transmitting apparatus to the line vm'res 12.

Indication code receiving apparatus is provided at the contr-ol office for conditioning switch and signal registrationrelays in accordance with indication codesreceived over the line wires 12. 'Ille indication registration relays are preferably of the magnetic stick type, and there is a bank of these relays, such as the relays 1WK, lLK and ZtRK, provided at the control oiice for each of the eld stations. A

Thecontrol ofeach bank of indication registration relays is by carrier receiving apparatus tuned to a fre'- f quency` characteristic of the field station for which the registration relays are provided. Thus, for the control ofV the registration relays lvWK, IRGK and ILGK for iield'station No. 1, for example, a Carrier Receiver F1 is provided at the control oice which is tuned to the carrier frequency transmitted by eld station No. 1, and a line' relay LFI is subject to energization by the output ofthe carrier receiver whereby this line relay is selectively responsive to code pulses transmitted only from 3 field station No. 1. The receiving apparatus for receiving from iield station No. 1 also includes a Step Timing Oscillator 17, Counting Relays 1S and Indication Application Circuits 19. It is to be understood that a similar bank of code receiving apparatus is provided at the control otice for each of the other eld stations. y

The code communication apparatus illustrated in FIG. 1B as being provided for eld station No. 1 is typical of the apparatus provided for each of the eld stations. The apparatus for receiving direct current control pulses transmitted over the line wires 12 from a control oice comprises a suitable line relay 1L connected to the line wires 12 through a Low Pass Filter 20. The control cycle steps are counted at field station No. l by counting relays 21, and the step periods are timed by Step Timing Oscillator 22.

A magnetic stick relay 1WZ is provided for controlling the operation of the power switch 1W, and signal control relays 1LGZ and IRGZ are provided for controlling the signals at iield station No. 1 for governing eastbound and westbound traic respectively.

Code transmitting apparatus is provided at field station No. 1 for transmitting selected indication codes to the control oce over the line wires 12 at a carrier frequency F1. Thus the transmitter at iield station No. 1 includes a Carrier Transmitter F1 which transmits at a frequency characteristic of field station No. 1 only.

The indication transmitting apparatus at field station No. 1 includes Automatic Start Apparatus 23 which is operable to initiate an indication cycle in response to a change in the condition of one of the devices at ield station No. 1. A Step Timing Oscillator 24 is provided for timing the steps during the transmission of an indication cycle, and a bank of Counting Relays 25 is provided for counting the steps of each indication cycle. Indication Code Selecting Apparatus 26 -is provided at iield station No. 1 for selecting the code characters to be transmitted during the respective steps of an indication cycle in accordance with the condition of the devices to have their positions indicated at the control oice.

Having thus described the general organization of the apparatus for one embodiment of the present invention, more specific consideration of this apparatus will now be given with respect to the mode of operation under certain typical operating conditions.

T o consider first the mode of operation for the communication of controls, it will be assumed that an operator desires to transmit controls to iield station No. 1 for setting up a route through the track switch 1W at the left-hand end of the passing siding 11. To initiate transmission to this iield station he actuates the start push button PB (see FIG. 1A) and closes contact 27 which is effective to initiate a control cycle. Similar push buttons (not shown) are provided for initiating transmission to the other iield stations. In accordance with the actuation of the start push button PB, the Step Timing Oscillator 13 is initiated, and the initiation of the cycle at the control oiiice is effective to pole change the line circuit and thus cause the relay NC to be dropped away and the relay PC to become picked up to actuate the line relay 1L at eld station No. 1 and the line relays L at the other field stations to initiate the Step Timing Oscillator at each of the field stations at substantially the same time.

In accordance with the oscillators being initiated at all stations including the control oice, the counting relays at all stations and at the control oice become active to count the steps of the control cycle. The line relays PC and NC are selectively energized during the several steps of the control cycle to apply selectively (-1-) and pulses through their contacts to the line wires 12 in accordance with code selecting apparatus 15 which selects first a station selection code, and then a code indica-tive of the switch and signal controls that have been designated At lield station No. 1, the actuation of the line relay 1L in response to the pole changing of the line circuit at the controlv oflice is effective by the opening of front contact 2S to deenergize the Step Timing Oscillator 22 to initiate a control cycle at that iield station. Contact 29 of relay 1L applies energy of one polarity or another to Control Application Circuitsso that station selection is accomplished dependent upon the reception of a code during the first part of the cycle assigned to iield station No. 1. Following the station selection portion of the cycle, `the relay 1WZ is actuated in accordance with the position of contact 29 during a particular step of the cycle, and the track switch 1W'is voperated to its normal or reverse position in accordance with the picked up or dropped away condition of the relay 1WZ, the circuit for the switch machine 18M for operating the track switch 1W being illustrated as selected in accordance with the position of contact 31 of relay 1WZ. Similarly, subsequent steps during the control cycle provide for the selective energization of the relays lLGZ and IRGZ in accordance with the code received. If relay 1LGZ is picked up during the cycle, the closure of ,its front contact 32 causes the clearing of the signal 1LA or signal 1LB dependent upon the position of the track switch 1W. If the relay IRGZ is picked up, the closure of its front contact 33 is effective to permit the clearing of signal 1RA or signal 1KB for governing eastbound trac through the track switch 1W, one or the other of these signals being selected in accordance with whether the track switch 1W is in its normal or reverse position. l

Having thus described how a control cycle of operation is effective for establishment of one route at one eld station, it should be readily apparent that a similar mode of operation is eiective for the establishment of other routes, and for the establishment of routes at any other field station that may be designated by the operator at the control ofce.

To consider the communication of indications from the ield stations to the control oice, it will be assumed that a cycle of operation for the transmission of indications is initiated at field station No. 1 by a change in the condition of one of the devices to have its position indicated at the control oce. Thus, upon operation of the track switch 1W from one position to another, for example, the switch repeater relay IWP is actuated, and the actua tion of this relay causes actuation of its contact 34 in a suitable start circuit. This is eiective to deenergize a normally energized start relay (not shown) which is maintained energized by a stick circuit including contacts 34, 35 and 36 of relays IWP, IRGP and lLGP respectively.

As is indicated by the block diagram in FIG. 1B, the automatic start apparatus starts the Step Timing Oscillator 24 land also is effective to cause the transmission of a distinctive carrier signalby carrier transmitter F1 over the line Wires 12 to the control office to initiate the Step Timing Oscillator 17 at t-he control oflice (see FIG. 1A). Such initiation at the conn'ol office is rendered effective by the opening of front contact 37 of the line relay LFI in the circuit which is normally effective for maintaining the Step Timing Oscillator 17 inactive.

After the indication cycle has been initiated, it is unnecessary to transmit an indication station code because separate receiving apparatus is provided at the control oice for receiving indications from each of the iield stations, the diierent field stations being identiiied at the control oice by reason of :the carrier frequency that is received. As the indication cycle progresses, distinctive characters are selected for transmission successively in yaccordance with the condition of the relays 1WP, IRGP and ILPG as is indicated by whether or not the contacts 38, 39 or 40 of these relays respectively are` open or closed.

It the relay 1WP is in its picked up position during an indication cycle, for example, a code character is transmitted via carrier frequency F1 over line wires 12 to the control office which selectively energizes the line relay LFI so as to cause the relay 1WK to be operated to ya corresponding position in accordance ywith the position of contact 41 of relay LF1. The relay IWK, therefore, is a registration relay which registers an indication of the condition of the track switch 1W at field station No. 1. Similarly the relays ILGK land lRGK at the control oice register indications as to the condition of the associated signals 1L and 1R respectively at field station No. 1.

Having thus described the mode of operation of the system for the communication of indications from field station No. 1 to the control office, it is to be understood that a similar mode of operation is effective for the cornmunication of indications from the other field stations to the control office, separate receiving apparatus being provided at the control ofce for the several field stations'.

It will therefore be readily apparent that all stations can transmit their indications at the same time, and that indications may be received simultaneously at the'control ofiice without interference, and it will also be readily apparent that controls may be transmitted from the control oice to the ydifferent field stations independent of whether or not indications are being transmitted over the line Wires 12 in as much as the direct current code pulses used for the transmission of controls will not interfere with the transmission of indications at their carrier frequencies and vice versa.

Having thus described a code communication system as applied to the centralized trame control of a particular track layout as one embodiment of the present invention, it is to be understood that this form of the invention is disclosed more particularly to facilitate the disclosure of the mode of operation and the principles involved in the invention, `and it is to be understood that various adaptations, alterations and modifications may be Kapplied to the specific form shown to meet the requirements of practice.

What I cl-aim is:

1. In a code communication system for the control from a control ofiice of devices at several remotely spaced field stations and for the indication Iat the control ofilce of conditions of said devices, indication transmitting means including a carrier transmitter operable at a distinctive frequency, a step counting relay chain and la step timing oscillator at each of the field stations for transmitting selected multiple element indication codes to the control ofce of the conditions of said devices, indication registering means at the control office for the several field stations, and indication code receiving means at the control office including carrier receivers, step counting relay chains and normally energized step timing oscillators lfor the several field stations for conditioning said indication registration means in accordance with the condition of thedevices at the several field stations as communicated by multiple element indication codes transmitted on the several carrier frequencies.

2. A code communication system for the communication from a control otlice to a plurality of remote field i stations of designated controls for devices at the field stations and for the communication of indications from the field stations to the control ofice of the conditions of the devices comprising in combination, code communication Iapparatus including a step counting relay chain and a normally -energized step timing oscillator at the control ofiice and at each of the field stations for communicating selected multiple element control codes from the control -ofrice to vthe field stations yfor the selective control of said ofiice in accordance with the multiple element indica-tion Y codes received indicative of the conditions of the devices at vthe several field stations. Y

3. A code communication system according to claim 2 wherein said code communication apparatus includes 'an unbroken line circuit to which direct current code pulses are applied at the control office through -a low pass filter. 4. A code communication system according to claim 3 wherein the carrier transmitters have their outputs applied to said 4line circuit.

5 A code communication system according to claim 4 wherein the` carrier transmitters at the sevenal eld stations have their outputs applied to said line circuit in multiple.

References Cited in the file of this patent UNITED STATES PATENTS Grondahl Apr. 2, 1932 1,869,847 l1,907,922 Bossart May 9, 1933 2,400,260 Miller 'May 14, 1946 2,581,056 Walmsley et al Ian. 1, 1952 2,627,063 Richards Ilan. 27, 1953 2,793,357 Wynn May 21, 1957 2,794,179 Sibley May 28, 1957 2,883,647

Leeds etal Apr. 21, 1959 

